For more than 20 years Germany’s largest helium cooling system operated reliably with a traditional centralized process control system. Rising maintenance costs for this aging system lead to the decision to modernize the system with a process control concept that relies on a decentralized I/O system over PROFIBUS and on a high-availability concept based on system redundancy. Softing’s enhanced PROFIBUS protocol software provided the foundation for achieving the redundancy concept with PROFIBUS by guaranteeing an instantaneous and bump-less switchover of all connected I/O devices